IEC 60079-28:2015/ISH1:2019 @IEC 2019 INTERNATIONAL ELECTROTECHNICAL COMMISSION IEC 60079-28 Edition2.02015-05 EXPLOSIVE ATMOSPHERES - Part 28: Protection of equipment and transmission systems using optical radiation INTERPRETATION SHEET 1 This interpretation sheet has been prepared by IEC technical committee 31: Equipment for explosiveatmospheres. The text of this interpretation sheet is based on the following documents: DISH Report on voting 31/1496/DISH 31/1508/RVDISH Full information on the voting for the approval of this interpretation sheet can be found in the report on voting indicated in the above table. Interpretation sheet to the 6th paragraph of the Scope of IEC 60079-28:2015 (Edition 2) Various interpretations are being made by IECEx ExCB -and ExTL staff regarding the consideration of the risk of ignition from optical sources, and the applicability of IEc 60o79-28 in the context of Subclause 6.6.4 of IEc 60079-0:2017. In addition to assistance provided to date on IECEx Decision Sheet DS2018/004, the Liaison with IECEx has indicated that an interpretation sheet addressing the applicability of IEC 60079-28 is required to clarify which equipment that falls into the scope and what does not. This interpretation is made available for Edition 2 of this standard due to the current use of IEC 60079-28:2015-05/ISH1:2019-10(en) that standard by manufacturers, conformity assessment schemes and national bodies by means of this "Interpretation Sheet" as follows: ICS29.260.20 IEC 60079-28:2015/ISH1:2019 - 2 - @IEC2019 Details of interpretation: IEc 60079-28:2015 (Edition 2: Protection of equipment and transmission systems using optical radiation Interpretation of the 6th paragraph of the Scope: Question: The 6th paragraph including the items 1) to 5) describes the equipment excepted from the Scope of this standard. The understanding of the listed exceptions is ambiguous. Therefore, it is possible that IEC 60079-28 is not applied in all situations where it is relevant. In addition, the potential confusion can be compounded by the wording of the exceptions. When should the requirements of IEC 60079-28 be applied to Ex Equipment, including EquipmentassembliesandExComponentsthatincludeanopticalradiationsourcebasedon Subclause 6.6.4 “Lasers, luminaries, and other non-divergent continuous wave optical sources" in IEC 60079-0:2017 (Edition 7)? Interpretation: This standard applies to i) laser equipment; and ii) optical fibre equipment; and ii) any other convergent light sources or beams where light is focussed in one single point within the hazardous area. NOTE 2 Some optical elements such as lenses and reflectors are able to convert divergent light into a convergent beam. This standard does not apply to: 1) laser equipment for EPL Mb, Gb or Gc and Db or Dc applications which complies with Class 1 limits in accordance with IEC 60825-1; or NOTE3ThereferencedClass1limitsarethosethatinvolveemissionlimitsbelow15mWmeasuredata distance from the optical radiation source in accordance with IEc60825-1,with this measured distance reflected inthe Exapplication. 2) divergent light sources or beams where light is not focussed within the hazardous area; or 3) Single or multiple optical fibre cables not part of optical fibre equipment if the cables: a) comply with the relevant industrial standards, along with additional protective means, e.g. robust cabling, conduit or raceway (for EPL Gb, Db, Mb, Gc or Dc); or b) comply with the relevant industrial standards (for EPL Gc or Dc).; or Optical radiation sources as defined in i. to ii. above where the optical radiation is fully 4） contained in an enclosure complying with one of the followings Types of Protection suitable for the EPL, or the minimum ingress protection rating specified: a) flameproof"d"enclosures (IEC 60079-1); or NOTE 4 A flameproof "d" enclosure is suitable because an ignition due to optical radiation in combination withabsorbers insidethe enclosure is contained. b) pressurized "p"enclosu